The biotic components of an ecosystem, like the producers, consumers and decomposers have definite relationships with reference to their number, biomass and energy. The graphical representation of the above relationship by pyramids is known as ecological pyramids. Three different types of ecological pyramids that exist among organisms are the pyramid of numbers, the pyramid of biomass and the pyramid of energy.
THE PYRAMID OF NUMBERS
The number of organisms decreases from producer level to carnivore level. This is called pyramid of number. In most ecosystems the pyramid of number is mostly erect or upright eg. Grass land, but in some cases the pyramid of number is inverted. eg. Numerousinsects live on a single huge tree. In this, number of individuals at the trophic level decreases from the producer level to the consumer level.
PYRAMID OF BIOMASS
The biomass generally decreases from producer level to carnivore level. This is called pyramid of biomass. It is mostly upright or erect. eg. Fallow land. In aquatic ecosystem the pyramid of biomass is inverted. eg. The combined weight of phytoplankton in a lake issmall as compared to weight of fish.
PYRAMID OF ENERGY
The amount of energy flow decreases from producer level to carnivore level, this is called pyramid of energy. The pyramid of energy isalways erect or upright. It indicates the total energy at each trophic level of the food chain. It also exhibits that at each trophic level, loss of energy and material takes place, as the processes of assimilation and growth. Thus, at the producer level, the total energy available is relatively more than at the higher trophic levels.